Multielectrode tube oscillator circuits



June 14, 1932. j HARRISON 1,863,372

MULTIELECTRODE TUBE OSCILLATOR CIRCUITS Filed July 51, 1928 iy'usfM/e 5,0161?? J IN V EN TOR.

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ATTORN Y Patented June 14, 1932 UNITED STATES PATENTJ OFFICE JAMISON R. HARRISON, OF MIDDLETOWN, CONNECTICUT, ASSIGNOR TO WIRED RADIO, INC., NEW YORK, N. Y., A CORPORATION OF DELAWARE MULTIELECTRODE TUBE OSCILLATOR CIRCUITS Application filed July 31,

ing multiple electrode thermionic vacuum tubes.

A better understanding can be had of the circuit arrangement of my invention by 'referring to the specification to follow and to the accompanying drawing which is a diegrammatic circuit arrangement showing the multi-electrode thermionic vacuum tube oscillator circuit of my invention.

The four electrode thermionic vacuum tube has been employed and its numerous advantages in many circuit arrangements are evident. The four electrode thermionic vacuum tube may be used as a space charge grid tube by impressing a positive potential on the inner grid or grid nearest the cathode. This accelerates the electron flow from the filament and provides convenient means for varying the mutual conductance of the tube. The four-electrode tube may be employed as an amplifier. In this case the plate and the inner or control grid/are carefully shielded from each other. This shielding efi'ect is accomplished by enclosing the plate with the second or outer or shielding grid. A positive potential from the plate supply battery is impressed on the shielding grid. This is done-so that the shielding grid will not block the electron flow from the filament to the plate. The object of the shielding grid is to reduce the interelectrode capacity between inner grid and plate to a minimum and thus minimize feedback action through the thermi onic vacuum tube.

In the five electrode thermionic vacuum tube circuit arrangement of my invention are to be found many improvements over 1928. Serial No. 296,586.

the systems and circuit arrangements heretofore employed. The advantage of controlling the electron strcam by the space charge grid, and the advantage of control by the shielding grid, are both realized in one system. Among the advantages of the circuit arrangement I employ are: (1) Radio frequency coupling between the grid and plate circuits is prevented; (2) the parameters of thermionic vacuum tubes may be simultaneously varied; (3) and the impedances of the system may be balanced or matched in a desired manner thereby improving the efliciency.

As shown in the drawing, a thermionic vacuum tube 15 having a cathode 5, inner or space charge grid 1, intermediate or control grid 2, outer or' shielding grid 3 and plate or anode 4, is employed in a constant frequency oscillator circuit arrangement. A mechanically vibratile element 6, which is illustrated as a crystal having piezo electric properties, is employed to maintain the frequency of the system uniform. Conductive members A, B, C and D in electrical relation with mechanically vibratile element 6 are movable and provide means for coupling the circuits of control grid 2-cathode 5. and of anode lrcathode 5. respectively to the piezo electric element 6. The plate circuit includes capacity 11 and inductance 12 having frequency characteristics corresponding to the approximate frequency characteristics of piezo electric element 6. A source of energy 7 energizes cathode 5. Source of energy 8 having the negative terminal connected to cathode 5 and the positive terminal connected to anode 4:, provides a positive potential for space charge grid 1 and shielding grid 3 by means of connections 9 and 10 respectively. The maximum mutual conductance of thermionic vacuum tube 15 can be obtained by providing the proper potential for space charge grid 1 in respect to negative potential of cathode 5. Shielding grid electrode 3 is supplied with a positive potential in respect to cathode 5. the value of which will exceed that supplied space charge grid 1 and will be less than the potential supplied anode 4. Oscillation of energy in the circuit arrangeand relative positioning provides means for obtaining the proper phase relation between control grid 2 and anode 4 and therefore the proper coupling of the input and output circuits for maximum power output.

It is obvious that the parameters of the thermionic vacuum tube employed may be varied by adjusting the potential supplied the electrodes of the thermionic vacuum tube and the coupling of the input and output circuits by means of conductive members A,B, C and D. It is likewise obvious that separate sources of energy may be employed in substitution for common source 8 and it is to be understood that the embodiments of my invention are not to be limited to the foregoing specification or to the accompanying drawing but only as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In an electron tube generator, in combination, an electron tube having filament, space charge grid, control grid, shielding grid, and plate electrodes, a source of potential connected to said filament, sources of potential for supplying potentials positive with respect to said filament to said space charge grid, shielding grid, and plate electrodes. said shielding grid being maintained at a greater positive potential with respect to said filament than said space charge grid,

and said plate being maintained at a greater positive potential with respect to said filament than said shielding grid. an input circuit connecting said control grid to said filament, an output circuit connecting said plate to said filament. and means for coupling said input and output circuits. whereby the electron stream between said filament and said plate is maintained and controlled.

2. In an electron tube generator, in combination, an electron tube having filament, space charge grid. control grid, shielding grid, and plate electrodes. a source of potential connected to said filament, sources of potential for supplying potentials positive with respect to said filament to said space charge grid. shielding grid, and plate electrodes, said shielding grid being maintained at agreater positive potential with respect to said filament than said space charge grid, and said plate being maintained at a greater positive potential with respect to said filament than said shielding grid, a piezo electric crystal element, a plurality of electrodes in electrical relation with said crystal element, an input circuit including said crystal element connecting said control grid to said filament, a plate circuit including said crystal element connecting said plate to said filament, whereby said crystal element couples said input circuit and said plate circuit.

3. In an electron tube generator, in combination, an electron tube having filament, space charge grid, control grid, shielding grid, and plate electrodes, a source of potential connected to said filament, sources of potential for supplying potentials positive with respect to said filament to said space charge grid, shielding grid, and plate electrodes, said shielding grid being maintained at a greater positive potential with respect to said filament than said space charge grid, and said plate being maintained at a greater positive potential with respect to said filament than said shielding grid, a piezo electric crystal element, two pairs of electrodes spaced from each other and in elcctri cal relation with said crystal element, the electrodes constituting a pair being positioned substantially opposite each other, one of the crystal electrodes of one pair being connected to said control grid, one of the crystal electrodes of said other pair being connected to said plate, and said other two crystal electrodes being connected together and to said filament.

4. In an electron tube generator, in combination an electron tube having filament, space charge grid, control grid, shielding grid, and plate electrodes, :1 source of potential connected to said filament, sources of potential for supplying potentials positive with respect to said filament to said space charge grid, shielding grid, and plate lectrodes, said shielding grid being maintained at a greater positive potential with respect to said filament than said space charge grid, and said plate being maintained at a greater positive potential with respect to said filament than said shielding grid, a piezo electric crystal element, two pairs of electrodes spaced from each other and in electrical relation with said crystal element, the electrodes constituting a pair being positioned substantially opposite each other, and means for varying the spacing between said two pairs of crystal electrodes. one of the crystal electrodes of one pair being connected to said control grid. one of the crystal electrodes of said other pair being connected to said plate, and said other two crystal electrodes being connected together and to said filament.

5. In an electron tube generator, in combination, an electron tube having filament. space charge grid, control grid, shielding grid, and plate electrodes, a source of potential connected to said filament, sources of potential for supplying potentials positive with respect to said filament, to said space charge grid, shielding grid, and plate electrodes, said shielding grid being maintained at a greater positive potential with respect to said filament than said space charge grid, and said plate being maintained at a greater positive potential with respect to said filament than said shielding grid, a mechanically vibratile element, two pairs of electrodes spaced from each other and in electrical relation with said vibratile element, the electrodes constituting a pair being positioned substantially opposite each other, one of the vibratile element electrodes of one pair being connected to said control grid, one of the vibratile element electrodes of said other pair being connected to said plate, and said other two vibratile element electrodes being connected together and to said filament.

6. In an electron tube generator, in combination, an electron tube having filament, space charge grid, control grid, shielding grid, and plate electrodes, a source of potential connected to said filament, sources of potential for supplying potentials positive with respect to said filament to said space charge grid, shielding grid, and plate electrodes, said shielding grid being maintained at a greater positive potential with respect to said filament than said space charge grid, and said plate being maintained at a greater positive potential with respect to said filament than said shielding grid, a piezo electric crystal element, two pairs of electrodes spaced from each other and in electrical relation with said crystal element, the electrodes constituting a pair being positioned substantially opposite each other, one of the crystal electrodes of one pair being connected to said control grid, one of the crystal electrodes of said other pair being connected to said plate, said other two crystal electrodes being connected together and to said filament, and a tuned load circuit connected between said plate and the positive terminal of said source of plate potential.

In testimony whereof I aflix my signature.

JAMISON R. HARRISON. 

